JP2018528101A - Multilayer film and method thereof - Google Patents

Abstract

Embodiments disclosed herein include a multilayer film having an adhesive layer and a release layer, the adhesive layer comprising: (i) an ethylene / alpha olefin elastomer; and (ii) ultra low density polyethylene, very low density polyethylene, Or a polyethylene polymer selected from combinations thereof, wherein the release layer has a density of 0.915-0.930 g / cc, a melt index I ₂ of 1.0-30.0 g / 10 min, and triple detection Low density polyethylene (LDPE) having a molecular weight distribution, (Mw / Mn) of 3.0 to less than 7.0, as measured by conventional calibration of pregelative gel permeation chromatography.
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Description

  Embodiments of the present disclosure generally relate to multilayer films, and more specifically to multilayer films that have high adhesion and are substantially free of polyisobutylene (PIB).

  Multilayer films are often used for packaging and can package a variety of items, such as small food store items such as meat and vegetables, from large amounts of farm materials such as grass and hay. For all of these items, it is generally robust and stretchable with a sufficient level of tack or tack so that the film can be peelably bonded to the film itself and / or the article wrapped in the film. It is desirable to have a film.

  In order to achieve the desired level of tackiness, additives such as PIB can be incorporated into the tacky layer to improve tackiness of the tacky layer. However, films containing such additives are 1) excessively noisy when unwound from film rolls when utilized on high speed packaging machines, and 2) additives move to the surface of the film during the aging period. Must be aged for a period of time (i.e., bloom), 3) contaminates the processing equipment, and 4) produces one-sided adhesive when single-sided adhesive is desired, etc. Can have the following disadvantages. Further, such additives can cause excessive handling problems when the additive is in liquid form and dripped excessively from the processing equipment.

  Multilayer films can also incorporate high levels of ethylene / alpha olefin elastomers to achieve higher levels of tack or tack, but ethylene / alpha olefin elastomers can make multilayer films very expensive. In addition, the film uses blow film techniques when the ethylene / alpha olefin elastomer is used at a high level (eg, greater than 90 wt% in the adhesive layer) due to the tack of the ethylene / alpha olefin elastomer. It can be difficult to process.

  Thus, an alternative multilayer film that has improved properties such as high tack and / or low noise, while being cost effective and / or relatively easy to fabricate using blown film techniques May be desired.

A multilayer film is disclosed in the embodiments herein. The multilayer film has an adhesive layer and a release layer. The adhesive layer comprises (i) an ethylene / alpha olefin elastomer having a density in the range of 0.855 to 0.890 grams / cm ³ and a melt index (I ₂ ) in the range of 0.1 to 30 grams / 10 minutes; (Ii) a polyethylene polymer selected from ultra-low density polyethylene, very low density polyethylene, or combinations thereof, wherein the polyethylene polymer has a density in the range of 0.885 to 0.915 grams / cm ³ , 0 Melt index (I ₂ ) in the range of 1-30 grams / 10 minutes and a purge fraction greater than 20 percent as determined by the Crystallized Elution Fractionation (CEF) test method. The release layer was measured with a density of 0.915-0.930 g / cc, a melt index I ₂ of 1.0-30.0 g / 10 min, and a conventional calibration of triple detector gel permeation chromatography, 3 Low density polyethylene (LDPE) having a molecular weight distribution (Mw / Mn) of 0.0 to less than 7.0.

Also disclosed in the embodiments herein are methods for making multilayer films. The method includes co-extruding the adhesive layer composition with the release layer composition in an extruder to form a tube having the adhesive layer and the release layer, and cooling the tube to form a multilayer film. . The adhesive layer composition comprises (i) an ethylene / alpha olefin having a density in the range of 0.855 to 0.890 grams / cm ³ and a melt index (I ₂ ) in the range of 0.1 to 30 grams / 10 minutes. And (ii) a polyethylene polymer selected from ultra-low density polyethylene, very low density polyethylene, or combinations thereof, wherein the polyethylene polymer has a density in the range of 0.885 to 0.915 grams / cm ^3. With a melt index (I ₂ ) in the range of 0.1-30 grams / 10 minutes, and a purge fraction greater than 20 percent as determined by the Crystallized Elution Fractionation (CEF) test method. The release layer composition was measured with a density of 0.915-0.930 g / cc, a melt index I ₂ of 1.0-30.0 g / 10 min, and a conventional calibration of triple detector gel permeation chromatography. Low density polyethylene (LDPE) having a molecular weight distribution (Mw / Mn) of 3.0 to less than 7.0.

  Additional features and advantages of the embodiments are set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from that description, or may be described in the specification, including the detailed description that follows. Recognized embodiments and claims are recognized. It is understood that both the foregoing description and the following description are intended to describe various embodiments and to provide an overview or framework for understanding the nature and nature of the claimed subject matter. .

  Reference will now be made in detail to embodiments of multilayer films and materials used to make such films. The multilayer film can be used in stretch adhesive applications. However, it is noted that this is merely an illustrative example of the embodiments disclosed herein. Embodiments are applicable to other techniques that are susceptible to problems similar to those described above. For example, the multilayer film described herein may be used as an agricultural film such as a surface protective film, silage wrap, or other film such as shrink film, durable transport bags, liners, bags, stand-up pouches, detergent pouches, sachets, etc. All of which are within the scope of this embodiment.

  In the embodiments described herein, the multilayer film comprises an adhesive layer and a release layer. Optionally, one or more core layers may be positioned between the adhesive layer and the release layer. An adhesive layer is an outer layer of a multilayer film that has sufficient adhesive tack so that the adhesive layer of the multilayer film can form a peelable bond when contacted with a surface, such as the surface of the article or the surface of the release layer. The release layer is an outer layer of a multilayer film that exhibits low adhesion only to the adhesive layer. The release layer allows the adhesive / release layer interface on the roll to separate so that the multilayer film can be unwound from the spool without excessive force or the film being torn.

  The thickness of the adhesive layer and the release layer can vary over a wide range. In some embodiments, the adhesive layer has a thickness that is 5-50 percent of the total thickness of the film, 5-30 percent of the total thickness of the film, or even 10-30 percent of the total thickness of the film. obtain. The release layer may have a thickness that is 5-50 percent of the total thickness of the film, 5-30 percent of the total thickness of the film, or even 10-30 percent of the total thickness of the film. In some embodiments where one or more core layers are present, the one or more core layers are 0 to 90 percent of the total thickness of the film, 10 to 90 percent of the total thickness of the film, and 20 of the total thickness of the film. It may have a thickness that is -90 percent, 30-90 percent of the total thickness of the film, 40-90 percent of the total thickness of the film, or 40-80 percent of the total thickness of the film. The ratio of thickness between the adhesive layer, the release layer, and any optional core layer can be any ratio that provides the desired properties such as adhesion, release, and the like. In some embodiments, the multilayer film can have an adhesive layer thickness, a core layer thickness, and a release layer thickness in a ratio ranging from 1: 8: 1 to 3: 4: 3.

Adhesive layer The adhesive layer may comprise an ethylene / alpha olefin elastomer and a polyethylene polymer selected from ultra-low density polyethylene, very low density polyethylene, or combinations thereof. In some embodiments, the adhesive layer comprises an ethylene / alpha olefin elastomer and very low density polyethylene. In other embodiments, the adhesive layer comprises an ethylene / alpha olefin elastomer and very low density polyethylene. In further embodiments, the adhesive layer comprises an ethylene / alpha olefin elastomer, ultra low density polyethylene, and very low density polyethylene.

  In the embodiments described herein, the ethylene / alpha olefin elastomer may comprise greater than 50% by weight of units derived from ethylene. All individual values and subranges greater than 50% by weight are included and disclosed herein. For example, the ethylene / alpha olefin elastomer is at least 60%, at least 70%, at least 80%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, at least 99 wt%, at least 99.5 wt%, more than 50 wt% to 99 wt%, more than 50 wt% to 97 wt%, more than 50 wt% to 94 wt%, more than 50 wt% to 90 wt%, 70 wt% ˜99.5 wt%, 70 wt% to 99 wt%, 70 wt% to 97 wt%, 70 wt% to 94 wt%, 80 wt% to 99.5 wt%, 80 wt% to 99 wt%, 80 Wt% to 97 wt%, 80 wt% to 94 wt%, 80 wt% to 90 wt%, 85 wt% to 99.5 wt%, 85 wt% to 99 wt%, 85 wt% 97 wt%, 88 wt% to 99.9 wt%, 88 wt% to 99.7 wt%, 88 wt% to 99.5 wt%, 88 wt% to 99 wt%, 88 wt% to 98 wt%, 88% to 97%, 88% to 95%, 88% to 94%, 90% to 99.9%, 90% to 99.5%, 90% to 99% %, 90% to 97%, 90% to 95%, 93% to 99.9%, 93% to 99.5%, 93% to 99%, or 93% by weight May contain ˜97 wt% units derived from ethylene. The ethylene / alpha olefin elastomer may comprise less than 50% by weight of one or more alpha olefin comonomer derived units. All individual values and subranges less than 50% by weight are included and disclosed herein. For example, the ethylene / alpha olefin elastomer is less than 45%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 18%, less than 15%, Less than 10% by weight, less than 8% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, 0.2 to 15% by weight, 0.2 to 12% by weight, 0.2 to 10% Wt%, 0.2-8 wt%, 0.2-5 wt%, 0.2-3 wt%, 0.2-2 wt%, 0.5-12 wt%, 0.5-10 wt% 0.5-8 wt%, 0.5-5 wt%, 0.5-3 wt%, 0.5-2.5 wt%, 1-10 wt%, 1-8 wt%, 1-5 Wt%, 1-3 wt%, 2-10 wt%, 2-8 wt%, 2-5 wt%, 3.5-12 wt%, 3.5-10 wt%, 3.5- %, 3.5-7%, or 4-12%, 4-10%, 4-8%, or 4-7% by weight of one or more alpha olefin comonomer-derived units. May be included. The comonomer content is determined using any suitable technique, such as a technique based on nuclear magnetic resonance (“NMR”) spectroscopy, and for example, US Pat. No. 7,498,282, incorporated herein by reference. Can be measured by 13 C NMR analysis as described above.

  Suitable alpha olefin comonomers include those containing 3 to 20 carbon atoms (C3-C20). For example, the alpha olefin may be a C4-C20 alpha olefin, a C4-C12 alpha olefin, a C3-C10 alpha olefin, a C3-C8 alpha olefin, a C4-C8 alpha olefin, or a C6-C8 alpha olefin. In some embodiments, the alpha olefin consists of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene and 1-decene. Selected from the group. In other embodiments, the alpha olefin is selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene. In a further embodiment, the alpha olefin is selected from the group consisting of 1-hexene and 1-octene.

  Exemplary ethylene / alpha olefin elastomers for use in the adhesive layer are AFFINITY ™ (from Dow Chemical Company), ENGAGE ™ (from Dow Chemical Company), INFUSE ™ (from Dow Chemical Company), It is commercially available under the trade names EXACT (manufactured by ExxonMobil Chemical) and TAFMER ™ (manufactured by Mitsui Chemicals, Inc.). Suitable ethylene / alpha olefin elastomers are further described in US Pat. Nos. 5,272,236 (Lai et al.), 6,486,284 (Karande et al.), And 6,100,341 (Friedman). Which are described and incorporated herein by reference.

  Ethylene / alpha olefin elastomers can be produced using a single site catalyst. Methods for producing olefin polymers using single site catalysts are described in US Pat. Nos. 5,272,236 (Lai et al.) And 6,486,284 (Karande et al.), All of which Incorporated herein by reference. Single site catalyst systems can include metallocene and post metallocene catalysts. In an exemplary embodiment, the ethylene / alpha olefin elastomer can be produced by a metallocene catalyst or a post metallocene catalyst.

  In some embodiments, the ethylene / alpha olefin elastomer may include one or more olefin block copolymers. Olefin block copolymers are polymers comprising two or more chemically distinct regions or segments (referred to as “blocks”) that can be joined in a linear fashion, ie pendant or grafted to polymerized ethylene functionality. A polymer containing chemically distinct units joined end to end rather than in a manner. The block is the amount or type of comonomer incorporated, the density, the amount of crystallinity, the crystallite size, the type or degree of stereoregularity (isotactic or syndiotactic) that can be attributed to the polymer of such compositions. ), Regioregularity or regioregularity, the amount of branching (including long-chain or hyper-branching), homogeneity, or any other chemical or physical property. Suitable olefin block copolymers are further described in US Pat. No. 7,608,668, which is incorporated herein by reference.

  In the embodiments described herein, the ethylene / alpha olefin elastomer has a density in the range of 0.855 to 0.890 grams / cc. All individual values and subranges from 0.855 g / cc to 0.890 g / cc are included and disclosed herein. For example, in some embodiments, the ethylene / alpha olefin elastomer may have a density from 0.860 g / cc to 0.890 g / cc. In other embodiments, the ethylene / alpha olefin elastomer may have a density from 0.865 g / cc to 0.890 g / cc. Density can be measured according to ASTM D792.

In the embodiments described herein, the ethylene / alpha olefin elastomer has a melt index (I ₂ ) in the range of 0.1-30 grams / 10 minutes. All individual values and subranges from 0.1 to 30 grams / 10 minutes are included and disclosed herein. For example, in some embodiments, the ethylene / alpha olefin elastomer may have a melt index (I ₂ ) in the range of 0.1-20 grams / 10 minutes. In other embodiments, the ethylene / alpha olefin elastomer may have a melt index (I ₂ ) in the range of 0.1-15 grams / 10 minutes. In a further embodiment, the ethylene / alpha olefin elastomer may have a melt index (I ₂ ) in the range of 0.1-10 grams / 10 minutes. The melt index (I ₂ ) can be measured according to ASTM D1238 (conditions 190 ° C./2.16 kg).

  The ethylene / alpha olefin elastomer is the amount of other polymers (eg, ULDPE or very low density polyethylene, and VLDPE or very low density polyethylene), the desired tack / tackiness; cost; tack stability during manufacture, transportation and storage And / or can be incorporated into the adhesive layer formulation in amounts based on various factors such as conditions of use. In some embodiments, the ethylene / alpha olefin elastomer is in the adhesive layer in the range of 10-90 weight percent of the adhesive layer, in the range of 15-90 weight percent of the adhesive layer, in the range of 30-90 weight percent of the adhesive layer. Or even present in an amount ranging from 40 to 85 weight percent of the adhesive layer. Of course, all individual values and subranges from 10 to 90 weight percent of the adhesive layer are included and disclosed herein.

  The adhesive layer also includes a polyethylene polymer selected from ULDPE, VLDPE, and combinations thereof. ULDPE and / or VLDPE is the amount of other components present in the adhesive layer (eg, ethylene / alpha olefin elastomer), the desired tack / adhesive properties in the film; cost; tack stability during manufacture, transportation and storage And / or can be incorporated into the adhesive layer formulation in amounts based on various factors such as conditions of use. In some embodiments, ULDPE and / or VLDPE is in the adhesive layer in the range of 10-90 weight percent of the adhesive layer, in the range of 20-85 weight percent of the adhesive layer, in the range of 30-70 weight percent of the adhesive layer, Or even present in an amount ranging from 35 to 70 weight percent of the adhesive layer.

  ULDPE or VLDPE, in polymerized form, contains a majority weight percent of units derived from ethylene, based on the total weight of ULDPE or VLDPE. The ULDPE or VLDPE can be an interpolymer of ethylene and at least one ethylenically unsaturated comonomer. In some embodiments, the comonomer is a C3-C20 alpha olefin. In other embodiments, the comonomer is a C3-C8 alpha olefin. In further embodiments, the C3-C8 alpha olefin is selected from propylene, 1-butene, 1-hexene, or 1-octene. In still further embodiments, the ULDPE or VLDPE can be an ethylene / propylene copolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / octene copolymer.

ULDPE or VLDPE can be made using the Ziegler-Natta catalyst method to produce the desired level of purge fraction. Ziegler-Natta catalysts are described in US Patent Publication Nos. 2008/0038571 (Klitzmiller et al.) And 2008/0176981 (Biscoglio et al.), Which are incorporated herein by reference in their entirety. In some embodiments, the Ziegler-Natta catalyzed ULDPE or VLDPE is 3.5 to 10.5 mol percent selected from the group consisting of ethylene and C ₃ -C ₂₀ α-olefins, dienes, and cycloalkenes. A copolymer with at least one comonomer. “ULDPE” and “VLDPE” may be used interchangeably. See, eg, US Patent Publication No. 2008/0038571 (Klitzmiller et al.), Which is incorporated by reference herein in its entirety. In some embodiments, VLDPE refers to ULDPE or VLDPE produced by a gas phase reaction method, and ULDPE refers to ULDPE or VLDPE produced by a liquid phase (solution) reaction method. A suitable ULDPE includes ATTANE ™ 4404 available from Dow Chemical Company. A suitable VLDPE includes DFDB-9042 NT VLDPE available from Dow Chemical Company.

  In the embodiments described herein, the polyethylene polymer has a density of 0.885 to 0.915 g / cc. All individual values and subranges from 0.885 to 0.915 g / cc are included and disclosed herein. For example, in some embodiments, the polyethylene polymer has a density of 0.885 to 0.910 g / cc. In other embodiments, the polyethylene polymer has a density of 0.890 to 0.915 g / cc. In a further embodiment, the polyethylene polymer has a density of 0.890 to 0.912 g / cc. In still further embodiments, the polyethylene polymer has a density of 0.895-0.905 g / cc. In yet a further embodiment, the polyethylene polymer has a density of 0.899-0.905 g / cc. Density can be measured according to ASTM D792.

In the embodiments described herein, the polyethylene polymer has a melt index (I ₂ ) in the range of 0.1-30 grams / 10 minutes. All individual values and subranges from 0.1 to 30 grams / 10 minutes are included and disclosed herein. For example, in some embodiments, the polyethylene polymer has a melt index (I ₂ ) in the range of 0.1-25 g / 10 minutes. In other embodiments, the polyethylene polymer has a melt index (I ₂ ) in the range of 0.1-20 g / 10 minutes. In a further embodiment, the polyethylene polymer has a melt index (I ₂ ) in the range of 0.1-15 g / 10 minutes. In yet a further embodiment, the polyethylene polymer has a melt index in the range of 0.1 to 10 g / 10 min _{(I 2).} In still further embodiments, the polyethylene polymer has a melt index (I ₂ ) in the range of 0.5 to 10 grams / 10 minutes. The melt index (I ₂ ) can be measured according to ASTM D1238 (conditions 190 ° C./2.16 kg).

In embodiments described herein, the polyethylene polymer can have a molecular weight distribution ( _Mw / _Mn ) of 3.0 to 6.0. Molecular weight distribution can be described as the ratio of number average molecular weight (M _n ) to weight average molecular weight (M _w ) (ie, M _w / M _n ) and can be measured by conventional gel permeation chromatography methods.

  In the embodiments described herein, the polyethylene polymer has a purge fraction greater than 20 percent as determined by the Crystallized Elution Fractionation (CEF) test method. The purge fraction can be produced during the polymerization process via a Ziegler-Natta catalyst (“ZN” catalyst) and is a branched (eg, highly branched) amorphous polyolefin that becomes part of the final polyethylene product. A copolymer may be qualitatively referred to. Without being bound by theory, a polyethylene polymer having a purge fraction of at least 20% by weight as determined by the CEF test method is blended with an ethylene / alpha olefin elastomer to provide an adhesive layer having desirable adhesive properties. I think it can be done. In some embodiments, the polyethylene polymer has a purge fraction greater than 22 percent, or greater than 25 percent. In other embodiments, the polyethylene polymer can have a purge fraction of less than 45 percent, or less than 40 percent. Of course, it should be understood that polyethylene polymers having higher purge fraction amounts may be utilized.

  Without being bound by theory, the combination of (i) an ethylene / alpha olefin elastomer and (ii) a polyethylene polymer having a purge fraction greater than 20 percent results in a higher level of PE (polyethylene) elastomer, and It is believed that similar or enhanced tackiness can be provided to the tacky layer as compared to a tacky layer that does not have a polyethylene polymer with a purge fraction greater than 20 percent. Specifically, an ethylene / alpha olefin elastomer can provide a smooth surface (ie, better surface conformability) to the adhesive layer, while a polyethylene polymer having a purge fraction greater than 20 percent is a polymer interface. It is believed that the overall diffusion mechanism can allow entanglement to form within the polymer matrix. PE elastomers can be relatively expensive and / or difficult to process in the blow film process when used at relatively high levels (eg, greater than 90% by weight of the layer) due to their tack. As it may be, it can be advantageous to reduce the amount of PE elastomer in the adhesive layer to provide the desired adhesive properties. Further, the adhesive layer may have desired adhesive properties without polyisobutylene (PIB) (ie, without PIB). Eliminating the need for a PIB additive is because the additive is sometimes subjected to a time-consuming aging period to move the additive to the surface of the film (ie, bloom). Can be advantageous. In addition, the additive can be in liquid form and can therefore be dripped excessively from processing equipment. In addition, the additives can contaminate processing equipment, cause excessive noise when the roll of film is not controlled, and / or cause sticking on both sides when not desired.

  The polyethylene polymer (ULDPE and / or VLDPE) reduces the amount of ethylene / alpha olefin elastomer present in the adhesive layer while at the same time still entering the adhesive layer at a level sufficient to provide the desired adhesive properties. Can be incorporated. This can be advantageous because ethylene / alpha olefin elastomers can be more effective than polyethylene polymers (ULDPE and / or VLDPE). In addition, ethylene / alpha olefin elastomers use blow film methods for their tack, especially when the ethylene / alpha olefin elastomer is present at relatively high levels (eg, greater than 90% by weight) in the adhesive layer. And can be difficult to process. In some embodiments, the adhesive layer can include 30 wt% to 70 wt% polyethylene polymer (ULDPE and / or VLDPE) and 70 wt% to 30 wt% ethylene / alpha olefin elastomer.

Optionally, the adhesive layer can include one or more additives and / or additional polymers. For example, in some embodiments, the adhesive layer can optionally include low density polyethylene (LDPE) and / or linear low density polyethylene (LLDPE). The low density polyethylene may have a density in the range of 0.915 to 0.935 grams / cm ³ and a melt index in the range of 0.1 to 30 grams / 10 minutes. The linear low density polyethylene may have a density / cm ^{3 in} the range of 0.912 to 0.940 grams and a melt index in the range of 0.5 to ³⁰ grams / 10 minutes. The adhesive layer can comprise LDPE in an amount of 0-30 weight percent of the adhesive layer. The adhesive layer can include LLDPE in an amount of 0-30 weight percent of the adhesive layer. In some embodiments, the adhesive layer may comprise LDPE in an amount of 0-30 weight percent of the adhesive layer and LLDPE in an amount of 0-30 weight percent of the adhesive layer.

  The ethylene / alpha olefin elastomer can be dry blended with a polyethylene polymer to form an adhesive layer blend. Methods for dry blending resins can be found in US Pat. No. 3,318,538 (Needham), which is incorporated herein by reference in its entirety. The ethylene / alpha olefin elastomer can also be melt blended with a polyethylene polymer to form an adhesive layer blend. Methods for melt blending resins can be found in US Pat. No. 6,111,019 (Arjunan et al.), Which is incorporated herein by reference in its entirety. The adhesive layer blend may be used in an extrusion process to form an adhesive layer, for example, via a blow film method.

Release layer The release layer comprises low density polyethylene (LDPE). In embodiments described herein, the release layer comprises 50 wt% to 100 wt% LDPE. All individual values and subranges from 50% to 100% by weight are included and disclosed herein. For example, in some embodiments, the release layer is 55% to 100%, 60% to 100%, 65% to 100%, 70% to 100%, 75% by weight of the release layer. % To 100%, 80% to 100%, 85% to 100%, 90% to 100%, 95% to 100% LDPE.

  The low density polyethylene can have a density from 0.915 g / cc to 0.930 g / cc. All individual values and subranges from 0.915 g / cc to 0.930 g / cc are included and disclosed herein. For example, in some embodiments, the low density polyethylene is 0.917 g / cc to 0.930 g / cc, 0.917 g / cc to 0.928 g / cc, 0.917 g / cc to 0.925 g / cc, Or it may have a density of 0.919 g / cc to 0.925 g / cc. Density can be measured according to ASTM D792.

  The low density polyethylene can have a melt index, i.e., I2 from 1.0 g / 10 min to 30.0 g / 10 min. All individual values and subranges from 1.0 g / 10 min to 30.0 g / 10 min are included and disclosed herein. For example, in some embodiments, the low density polyethylene is 1.0-25.0 g / 10 min, 1.0-20.0 g / 10 min, 1.0-15.0 g / 10 min, 1.0 -10.0 g / 10 min, 1.0-8.0 g / 10 min, 1.0-5.0 g / 10 min, 1.0-3.0 g / 10 min, 1.5-2.75 g / 10 Or a melt index of 1.75 to 2.75 g / 10 min. The melt index I2 can be measured according to ASTM D1238 (190 ° C. and 2.16 kg).

  The low density polyethylene can have a molecular weight distribution (MWD or Mw / Mn) of 3.0 to less than 7.0, as measured by conventional calibration of triple detector gel permeation chromatography (TDGPC). All individual values and subranges from 3.0 to less than 7.0 are included and disclosed herein. For example, in some embodiments, the low density polyethylene is 3.0-6.8, 3.0-6.6, 3.0-6.5, 3.5-6. It can have an MWD of 6, 3.5-6.5, 4.0-6.6, or 4.0-6.5. The TDGPC test method is outlined below.

  In the embodiments described herein, the low density polyethylene may have a number average molecular weight of 10,000 to 20,000 g / mol as measured with a conventional calibration of TDGPC. All individual values and subranges from 10,000 to 20,000 g / mol are included and disclosed herein. For example, in some embodiments, the low density polyethylene has a number average molecular weight of 12,000-18,000 g / mol, or 14,000-17,000 g / mol, as measured by conventional calibration of TDGPC. Can do.

  In the embodiments described herein, the low density polyethylene can have a weight average molecular weight of 75,000 to 95,000 g / mol as measured by conventional calibration of TDGPC. All individual values and subranges from 75,000 to 95,000 g / mol are included and disclosed herein. For example, in some embodiments, the low density polyethylene has a weight average molecular weight of 77,000 to 93,000 g / mol, or 80,000 to 91,000 g / mol, as measured by conventional calibration of TDGPC. Can do.

  In the embodiments described herein, the low density polyethylene can have a z-average molecular weight of 250,000 to 300,000 g / mol as measured with a conventional calibration of TDGPC. All individual values and subranges from 250,000 to 300,000 g / mol are included and disclosed herein. For example, in some embodiments, the low density polyethylene has a z-average molecular weight of 260,000 to 290,000 g / mol, or 270,000 to 285,000 g / mol, as measured with a conventional calibration of TDGPC. Can do.

  In the embodiments described herein, the low density polyethylene can have an absolute weight average molecular weight of 130,000 to 185,000 g / mol as measured by TDGPC. All individual values and subranges from 130,000 to 185,000 g / mol are included and disclosed herein. For example, in some embodiments, the low density polyethylene can have an absolute weight average molecular weight of 140,000 to 170,000 g / mol, or 155,000 to 163,000 g / mol, as measured by TDGPC.

  In the embodiments described herein, the low density polyethylene can have an absolute z-average molecular weight of 1,000,000-3,500,000 g / mol as measured by TDGPC. All individual values and subranges from 1,000,000 to 3,500,000 g / mol are included and disclosed herein. For example, in some embodiments, the low density polyethylene has an absolute of 1,400,000-3,300,000 g / mol, or 2,500,000-3,500,000 g / mol as measured by TDGPC. It can have a z-average molecular weight.

  In embodiments described herein, the low density polyethylene may have a Mw (abs) / Mn (conv) of 1.5 to 2.1 as measured by TDGPC. All individual values and subranges from 1.5 to 2.1 are included and disclosed herein. For example, in some embodiments, the low density polyethylene may have a Mw (abs) / Mn (conv) of 1.6 to 2.1, or 1.7 to 2.05 as measured by TDGPC. .

  In the embodiments described herein, the low density polyethylene can have a gpcBR of 1.0 to 1.9. All individual values and subranges from 1.0 to 1.9 are included and disclosed herein. For example, in some embodiments, the low density polyethylene can have a gpcBR of 1.3-1.8, 1.4-1.7, or 1.5-1.7 as measured by TDGPC. .

  In the embodiments described herein, the low density polyethylene can have a melt strength of 3-10 cN, measured at 190 ° C. All individual values and subranges from 3 to 10 cN are included and disclosed herein. For example, in some embodiments, the low density polyethylene may have a melt strength of 4-9 cN, or 4.5-9 cN, measured at 190 ° C.

  In the embodiments described herein, the low density polyethylene is from 3,000 to 7,000 Pa-s as measured by dynamic mechanical spectroscopy (DMS) method at 0.1 rad / sec, 190 ° C. It can have a viscosity. All individual values and subranges from 3,000 to 7,000 Pa-s are included and disclosed herein. For example, in some embodiments, the low density polyethylene is 4,000-7,000 Pa-s, or 5 measured at 0.1 rad / sec at 190 ° C. by dynamic mechanical spectroscopy (DMS) method. May have a viscosity of 3,000 to 6,000 Pa-s.

  In the embodiments described herein, the low density polyethylene has a viscosity ratio of 7-15 (viscosity at 0.1 rad / second divided by viscosity at 100 rad / second, both using DMS). Measured at 190 ° C.). All individual values and subranges from 7 to 15 are included and disclosed herein. For example, in some embodiments, the low density polyethylene is a viscosity ratio of 8-14, 9-13, or 10-12 (viscosity at 0.1 rad / sec divided by viscosity at 100 rad / sec, Both can have DMS measured at 190 ° C).

  In the embodiments described herein, the low density polyethylene may have a loss tangent at 0.1 rad / sec of 4.5-10, measured at 190 ° C. using DMS. All individual values and subranges from 4.5 to 10 are included and disclosed herein. For example, in some embodiments, the low density polyethylene has a loss tangent at 0.1 rad / sec of 5-7, or 5.5-6.5, measured at 190 ° C. using DMS. Can have.

LDPE is a peroxide (eg, as described herein) using any type of reactor or reactor configuration known in the art in an autoclave and / or tubular reactor, or any combination thereof. A partially or fully polymerized branched polymer at a pressure greater than 14,500 psi (100 MPa) using a free radical initiator such as U.S. Pat. No. 4,599,392 incorporated by reference). May be included. In some embodiments, the LDPE is a single designed to impart a high level of long chain branching, such as that described in PCT Patent Publication No. WO2005 / 023912, the disclosure of which is incorporated herein. It can be made in an autoclave process under phase conditions. In some embodiments, LDPE is made in an autoclave process in a two-phase region to produce LDPE with narrower molecular weight distribution and fewer long chain branches, resulting in LDPE with good optical and other film properties Can be done. The two-phase region in the high-pressure autoclave process is generally achieved at lower pressures and can also be achieved by the use of an inert anti-solvent such as nitrogen in the reaction mixture (Handbook of Vinyl Polymers: Radical Polymerization, Process, and Technology, 2 ^nd Edition, Edited by M. K. Misra and Y. Yagci, CRC Press, p. 382, 2009). In some embodiments, the LDPE has a narrower or moderate molecular weight distribution such as those described in PCT Patent Publication Nos. WO2011 / 019563 and WO2010 / 042390, the disclosures of which are incorporated herein by reference. It can be made in a tubular process under conditions to produce LDPE. In embodiments herein, the LDPE is a homopolymer. In some embodiments, the low density polyethylene does not contain sulfur. In some embodiments, the low density polyethylene contains less than 5 ppm, even less than 2 ppm, even less than 1 ppm, and even less than 0.5 ppm sulfur. Exemplary LDPE resins may include, but are not limited to, resins sold by Dow Chemical Company such as LDPE640I resin or LDPE608A. Other exemplary LDPE resins are described in WO2014 / 051682 and WO2012 / 082393, which are incorporated herein by reference.

In the embodiments described herein, the release layer can further comprise linear low density polyethylene (LLDPE). In some embodiments, the release layer is 1% to 100%, 1% to 50%, 1% to 40%, 1% to 30%, 1% to 1% by weight of the release layer. 25 wt%, 5 wt% to 40 wt%, 5 wt% to 30 wt%, 5 wt% to 25 wt%, 10 wt% to 40 wt%, 10 wt% to 30 wt%, or 10 wt% to 25 wt% It may further comprise LLDPE present in an amount in the range of weight percent. LLDPE is measured in accordance with ASTM D792 and has a density in the range of 0.912 to 0.940 grams / cm ³ , and 0.5 to 30 grams / minute as measured in accordance with ASTM D1238 (conditions 190 ° C./2.16 kg). It may have a 10-minute range of the melt index _{I 2.}

Core Layer Optionally, the multilayer film described herein can comprise one or more core layers positioned between the adhesive layer and the release layer. In some embodiments, the multilayer film comprises a single core layer positioned between the adhesive layer and the release layer. In other embodiments, the multilayer film comprises a single core layer positioned between and in contact with at least a portion of the adhesive layer and the release layer.

  The core layer may include one or more of LLDPE, LDPE, ethylene / alpha olefin elastomer, polypropylene elastomer, and / or ethylene vinyl acetate (EVA). In some embodiments, the core layer is 0-100 weight percent, 25-100 weight percent, 30-100 weight percent, 40-100 weight percent, 50-100 weight percent, 60-100 weight percent of the core layer, LLDPE in an amount of 65-100 weight percent, 70-100 weight percent, 75-100 weight percent. In other embodiments, the core layer comprises LLDPE and one or more of ethylene / alpha olefin elastomer, polypropylene elastomer, or ethylene vinyl acetate. One or more of the ethylene / alpha olefin elastomer, polypropylene elastomer, or ethylene vinyl acetate ranges from 1 to 30 weight percent, 1 to 25 weight percent, 1 to 20 weight percent, or 1 to 15 weight percent of the core layer. May be present in any amount. In further embodiments, the core layer may include LLDPE and LDPE. The LDPE can be present in an amount ranging from 1 to 50 weight percent, 1 to 35 weight percent, 1 to 25 weight percent, or 1 to 20 weight percent of the core layer. Exemplary LLDPEs for use in the core layer of a multilayer film are commercially available from Dow Chemical Company under the trade names ELITE ™, TUFLIN ™, and DOWLEX ™.

  The multilayer films described herein can be made by a variety of techniques such as a blown film method. A method for making a multilayer blown film is described in US Pat. No. 6,521,338 (Maka), the entirety of which is incorporated herein by reference. For example, in some embodiments, the multilayer blown film coextrudes the adhesive layer composition with the release layer composition (and optionally the core layer composition) in an extruder to create a tube having the adhesive layer and the release layer. And cooling the tube to form a multilayer blown stretched film.

  In the embodiments described herein, the multilayer film may exhibit a sufficiently high level of tack and / or a relatively reduced noise level that may occur when the multilayer film is unrolled. In some embodiments, the multilayer film exhibits a noise level of less than 90 decibels (dB) when the release layer comprises 100% by weight of the LDPE described herein. In some embodiments, the multilayer film exhibits an adhesion value of greater than 200 g when the release layer comprises 100% by weight of the LDPE described herein. In some embodiments, the multilayer film exhibits a noise level of less than 90 decibels (dB) and an adhesion value of greater than 200 g when the release layer comprises 100% by weight of the LDPE described herein.

  Multilayer film embodiments will now be further described in the following illustrative examples.

Test Method Density Density can be measured according to ASTM D-792.

Melt Index Melt index (I ₂ ) can be measured according to ASTM D-1238, Procedure B (conditions 190 ° C./2.16 kg). The melt index (I ₁₀ ) can be measured according to ASTM D-1238, Procedure B (conditions 190 ° C./10.0 kg).

Conventional gel permeation chromatography (GPC)
The chromatography system consisted of a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph equipped with an internal IR5 detector. The autosampler oven compartment was set at 160 degrees Celsius and the column compartment was set at 150 degrees Celsius. The columns used were three Agilent “Mixed B” 30 cm 10 micrometer linear mixed bed columns and one 10 um pre-column. The chromatography solvent used was 1,2,4 trichlorobenzene and contained 200 ppm butylhydroxytoluene (BHT). The solvent source was sparged with nitrogen. The injection volume used was 200 microliters and the flow rate was 1.0 milliliters / minute.

  Calibration of the GPC column set was performed with 21 narrow molecular weight distribution polystyrene standards with molecular weights in the range of 580-8,400,000 in six “cocktail” mixtures with at least a 10-fold separation between individual molecular weights. Arranged. The standard was purchased from Agilent Technologies. Polystyrene standards are prepared at 0.025 grams in 50 milliliters of solvent for molecular weights above 1,000,000 and 0.05 grams in 50 milliliters of solvent for molecular weights below 1,000,000. did. The polystyrene standard was dissolved at 80 ° C. for 30 minutes with slow stirring. Polystyrene standard peak molecular weight (described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)).

  (Wherein M is molecular weight, A has a value of 0.4315, and B is equal to 1.0) was used to convert to polyethylene molecular weight.

  A fifth order polynomial was used to fit each polyethylene equivalent calibration point. A small adjustment was made to A (approximately 0.415 to 0.44) to correct column resolution and band expansion effects so that NIST standard NBS 1475 was obtained at 52,000 Mw.

  The total plate count of the GPC column set was performed with Eicosane (prepared at 0.04 g in 50 ml TCB and dissolved for 20 minutes with slow agitation). Plate count (Equation 2) and symmetry (Equation 3) were measured for 200 microliter injections according to the following equation:

  Where RV is the retention capacity in milliliters, the peak width is milliliters, the peak maximum is the maximum height of the peak, and ½ height is ½ the peak maximum height. is there.

  Where RV is the retention capacity in milliliters, peak width is milliliters, peak maximum is the peak maximum position, 1/10 height is 1/10 the peak maximum height, The backward peak refers to the peak tail at the retention capacity after the peak maximum, and the forward peak refers to the peak front at the retention capacity after the peak maximum. The plate count of the chromatography system must be greater than 24,000 and the symmetry should be between 0.98 and 1.22.

  Samples were prepared in a semi-automated manner using PolymerChar's “Instrument Control” software, the sample weight target was 2 mg / ml and the solvent (containing 200 ppm BHT) was passed through a PolymerChar high temperature autosampler. And added to a septum cap vial previously sparged with nitrogen. The sample was dissolved at 160 degrees Celsius for 2 hours under “slow” vibration.

  Calculations of Mn, Mw, and Mz were obtained from GPC using the PolymerChar GPC-IR chromatograph internal IR5 detector (measurement channel) according to equations 4-6, using PolymerChar GPCone ™ software, each etc. Based on the IR equivalent chromatogram minus the reference value at the interval data collection point (i) and the polyethylene equivalent molecular weight obtained from Equation 1 and the narrow standard calibration curve of point (i).

  To monitor the deviation over time, a flow marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. Using this flow rate marker, the flow rate of each sample was linearly corrected to that of the decane peak in the narrow standard calibration by alignment of each decane peak in the sample. It was then speculated that any change during the decan marker peak was associated with a linear shift in both flow rate and chromatographic slope. To facilitate the highest accuracy of flow marker peak RV measurements, the least squares fitting procedure was used to fit the flow marker concentration chromatogram peaks to a quadratic equation. The first derivative of the quadratic equation was then used to determine the true peak position. After calibrating the system based on the flow marker peak, the effective flow (as a measure of the calibration slope) is calculated as Equation 7. Flow marker peak processing was performed by PolymerChar GPCone (TM) software.

Triple detector gel permeation chromatography (TDGPC)
The chromatographic system includes a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph with an internal IR5 infrared detector (IR5), and a Precision Detector (Now Agilent Technologies) two-angle laser light scattering (LS) detector model 2040. It consisted of a connected 4-capillary viscometer (DV). For all light scattering measurements, an angle of 15 degrees was used for measurement purposes. The autosampler oven compartment was set at 160 degrees Celsius and the column compartment was set at 150 degrees Celsius. The columns used were four Agilent “Mixed A” 30 cm 20 micrometer linear mixed bed columns and a 20 um pre-column. The chromatography solvent used was 1,2,4 trichlorobenzene and contained 200 ppm butylhydroxytoluene (BHT). The solvent source was sparged with nitrogen. The injection volume used was 200 microliters and the flow rate was 1.0 milliliters / minute.

  Calibration and Calculation Conventional molecular weight moments and distributions (using a 20 um “Mixed A” column) were performed according to the above method similar to a conventional GPC procedure using a “Mixed B” column.

  A systematic approach for the determination of multi-detector offsets is described by Balke, Mourey, et. al. (Mauley and Balk, Chromatography Polym. Chpt 12, (1992)) (Balke, Thitratsakul, Lew, Cheung, Murey, Chromatography Polym. Chr, published in Ch. 13, 1992) Using GPCONe ™ software, triple detector logs (MW and IV) results from a wide homopolymer polyethylene standard (Mw / Mn> 3) can be converted to a narrow standard column calibration from a narrow standard calibration curve. Optimize for results.

  Absolute molecular weight data were obtained from Zimm (Zimm, BH, J. Chem. Phys., 16, 1099 (1948)) and Kratochvir (Kratochville, P., Classic Lighting Scattering from Polymer Solutions, Elsever 198, Elsever, Elsevder, 1981). )) In a manner consistent with that published by PolymerChar GPCone (TM) software. The total injected concentration used in the determination of molecular weight is from the mass detector area and mass detector constant obtained from one of the suitable linear polyethylene homopolymers or polyethylene standards of known weight average molecular weight. Obtained. The calculated molecular weight (using GPCOne ™) uses the light scattering constant obtained from one or more of the polyethylene standards described below and the refractive index concentration coefficient dn / dc of 0.104. I got it. In general, the mass detector response (IR5) and light scattering constant (determined using GPCOne ™) should be determined from a linear standard having a molecular weight greater than about 50,000 g / mol. Viscometer calibration (determined using GPCone ™) was performed using the method described by the manufacturer or alternatively, Standard Standard (SRM) 1475a (National Institute of Standards and Technology (NIST) Can be achieved by using published values of suitable linear standards such as A specific viscosity area (DV) of the calibration standard and the viscometer constant (obtained using GPCOne ™) relating the injected mass to its intrinsic viscosity is calculated. The chromatographic concentration was assumed to be low enough to remove the corresponding second vial factor effect (concentration effect on molecular weight).

The absolute weight average molecular weight (Mw (abs)) is integrated by the area of light scattering (LS), and the integrated chromatogram (factored by the light scattering constant) is taken out from the mass constant and mass detector (IR5) area. Obtained from the removal (using GPCOne ™). The molecular weight and intrinsic viscosity response are extrapolated to the end of the chromatography where noise is reduced from the signal (using GPCone ™). The other respective moments Mn _(Abs) and Mz _(Abs) are given according to equations 8-9 as follows:

From the absolute intrinsic viscosity (IV _(Abs) ) divided by the mass taken (using GPCONe ™) the chromatogram (factored by the viscosity constant) integrated by the intrinsic viscosity (DV) area. (Using GPCOne ™).

  gpcBR is determined from the TDGPC data measured above and calculated as described in WO2014 / 051682.

  For all of the TPGPC data reported herein, three replicates are performed for each sample, an average is taken, and the average value is reported herein.

Crystallization Elution Fractionation (CEF) Method The crystallization elution fractionation (CEF) method is described in Monlabal et al, Macromol. Symp. 257, 71-79 (2007). The CEF machine includes an IR-4 or IR-5 detector (eg, commercially available from PolymerChar, Spain) and a two-angle light scatter detector model 2040 (eg, commercially available from Precision Detectors). A 50 mm x 4.6 mm 10 micrometer guard column (eg, commercially available from PolymerLabs) is installed in the detector oven in front of the IR-4 or IR-5 detector. Orthodichlorobenzene (ODCB, 99% anhydrous grade) and 2,5-di-tert-butyl-4-methylphenol (BHT) (eg, commercially available from Sigma-Aldrich) were obtained. Silica gel 40 (particle size 0.2-0.5 mm) (eg, commercially available from EMD Chemicals) was also obtained. The silica gel is dried in a vacuum oven at 160 ° C. for at least 2 hours before use. ODCB is sparged with dry nitrogen (N ₂ ) for 1 hour before use. Dry nitrogen is obtained by passing nitrogen at <90 psig over CaCO ₃ and 5 molecular sieves. By adding 5 grams of dry silica to 2 liters of ODCB or by pumping through a column (s) packed with dry silica at 0.1 ml / min to 1.0 ml / min, Dry further. If an inert gas such as N ₂ is not used to purge the sample vial, add 800 milligrams of BHT to 2 liters of ODCB. Dry ODCB, with or without BHT, will be referred to herein as “ODCB-m”. A sample solution is prepared by dissolving the polymer sample in ODCB-m at 4 mg / ml for 2 hours at 160 ° C. while shaking using an autosampler. Inject 300 μL of sample solution into the column. The temperature profile of CEF is as follows: crystallization from 110 ° C. to 30 ° C. at 3 ° C./min, thermal equilibration at 30 ° C. for 5 minutes (including soluble fraction elution time set at 2 minutes), and 30 Elution from ℃ to 140 ℃ at 3 ℃ / min. The flow rate during crystallization is 0.052 ml / min. The flow rate during elution is 0.50 ml / min. IR-4 or IR-5 signal data is collected at one data point / second.

  U.F. on CEF column. S. Fill glass beads at 125 μm ± 6% with 1/8 inch stainless tube according to 8,372,931 (eg, commercially available from MO-SCI Specialty Products with acid detergent). The internal liquid volume of the CEF column is 2.1 ml to 2.3 ml. Temperature calibration is performed by using a mixture of NIST standard linear polyethylene 1475a (1.0 mg / ml) and Eicosane (2 mg / ml) in ODCB-m. The calibration includes (1) calculating a lag volume defined as a temperature offset between Eicosane's measured peak elution temperature-30.00 ° C, and (2) subtracting the temperature offset of elution temperature from the CEF raw temperature data. (Note that this temperature offset is a function of experimental conditions such as elution temperature, elution flow rate, etc.), (3) NIST linear polyethylene 1475a has a peak temperature at 101.00 ° C. and Eicosane is Creating a linear calibration line that converts the elution temperature over the range of 30.00 ° C. to 140.00 ° C. to have a peak temperature of 30.00 ° C., and (4) solubility measured isothermally at 30 ° C. For the fraction, the elution temperature consists of four steps: linearly extrapolated by using an elution heating rate of 3 ° C./min. Reported elution peak temperatures are obtained so that the observed comonomer content calibration polarity matches that previously reported in USP 8,372,931.

  A CEF chromatogram is generally divided into three zones, and each zone of the CEF chromatogram has a certain elution temperature range. The weight percent of the lowest temperature zone is commonly referred to as the weight percent of zone 1 or the weight percent of the purge fraction. The weight percent of the intermediate temperature zone is commonly referred to as the weight percent of zone 2 or the weight percent of the copolymer fraction. The weight percent of the highest temperature zone is commonly referred to as the weight percent of zone 3 or the weight percent of the dense fraction.

Melt strength Melt strength was fed in a Goettfert Rheotester 2000 capillary rheometer with a flat inlet angle (180 degrees) of 30 mm length and 2.0 mm diameter, Goettfert Rheotens 71.97 (Goettfert Inc., Rock Hill , SC) and measured at 190 ° C. The pellets (20-30 gram pellets) are fed into a barrel (length = 300 mm, diameter = 12 mm), compressed and allowed to melt for 10 minutes before 38.2 s ⁻¹ walls at a given die diameter Extrusion was performed at a constant piston speed of 0.265 mm / sec corresponding to the shear rate. The extrudate was passed through a Rheotens wheel located 100 mm at the die exit and pulled with a downward wheel at an acceleration rate of 2.4 mm / s ² . The force applied (in cN) on the wheel was recorded as a function of the wheel speed (in mm / sec). The melt strength is reported as the plateau force before the strand breaks.

Dynamic mechanical spectroscopy (DMS)
Rheological measurements to determine the viscosity at 0.1 rad / sec, the viscosity at 100 rad / sec, and the loss tangent at 0.1 rad / sec were performed at 190 ° C. and 10% strain in a nitrogen environment. The punched disc is placed between two “25 mm” parallel plates located in an ARES-1 (Rheometrics SC) rheometer oven preheated at 190 ° C. for at least 30 minutes, with a gap of “25 mm” parallel plates of 2.0 mm Slowly decreased. The sample was then allowed to stay exactly 5 minutes under these conditions. The oven was then opened and excess sample was carefully cut around the edge of the plate and the oven was closed. The method had an additional 5 minute delay incorporated to allow temperature equilibration. The viscosity at 0.1 rad / sec, the viscosity at 100 rad / sec, and the loss tangent at 0.1 rad / sec are then measured by small amplitude, oscillating shear following a frequency sweep increasing to 0.1-100 rad / sec. did. Complex viscosity η *, Tan (delta) or loss tangent, viscosity at 0.1 rad / sec (V0.1), viscosity at 100 rad / sec (V100), and viscosity ratio (V0.1 / V100) It was calculated from the data.

Tackiness Stretch tack on a pallet (of stretch tack performance) can be measured by Lantech SHS test equipment. The test consisted of stretching 6 rolls at 200% with a constant force F2 of 8 pounds using a turntable operating at a speed of 10 rpm. The end of the film is then attached to a load cell that measures the force in grams required to tear off the drum.

Noise The level of film noise during unwinding can be determined by the Highlight Stretch Film Test (from Highlight Industries). As the film is unwound from the sample roll, a sensor attached to the apparatus and 5 inches away from the film roll measures the noise. The unwinding speed is 355 ft per minute and the stretch level is 250%.

Adhesive Layer and Core Layer Table 1 shows the resins used in the adhesive layer and the core layer. The resins in Table 1 are available from Dow Chemical Company.

  The core layer consists of 100% by weight DOWLEX ™ 2045G LLDPE. The adhesive layer consists of 65% by weight of AFFINITY ™ EG 8100G PE elastomer and 35% by weight of Sample 1 ULDPE.

Sample 1 Preparation of Ziegler-Natta (ZN) Catalyst for Making ULDPE A ZN catalyst was prepared according to the following procedure. Ethyl aluminum dichloride (EADC) solution (Isopar E (15 wt% EADC dissolved in ExxonMobil Chemical Co., Houston, Tex.)) Was added to a magnesium chloride (MgCl ₂ ) slurry (0.2 M in Isopar E). And aged with stirring for 6 hours before use. Titanium tetraisopropoxide (Ti (OiPr) ₄ ) was transferred to a MgCl ₂ / EADC slurry vessel followed by aging for at least 8 hours to obtain a precursor catalyst. The ratio of MgCl ₂ : EADC: Ti (OiPr) ₄ was such that the metal ratio (Mg: Al: Ti) in the precursor catalyst was 40: 12.5: 3.

Sample 1 Preparation of ULDPE A solution polymerization reactor system was used. Hydrocarbon solvent and monomer (ethylene) were injected into the reactor as a liquid. Comonomer (1-octene) was mixed with the liquid solvent. This feed stream was cooled to below 20 ° C. and then injected into the reactor system. The reactor system was operated at a polymer concentration greater than 10% by weight. The adiabatic temperature rise of the solution is the main cause of heat removal from the polymerization reaction.

  The solvent used in the solution polyethylene process was a high purity isoparaffin fraction of C6-C8 hydrocarbons. Fresh 1-octene was purified and mixed with a recycle solvent stream (containing solvent, ethylene, 1-octene, and hydrogen). After mixing with the recycle stream, the combined liquid streams were further purified before pumping the contents into the reactor using a 600-1000 psig pressure feed pump. Fresh ethylene was purified and compressed to 600-1000 psig. Hydrogen (telogen used to reduce molecular weight) and ethylene were flow controlled into the recycle solvent stream and the entire feed stream was cooled to an appropriate feed temperature that could be <40 ° C. The process used the Ziegler-Natta catalyst described above to catalyze the polymerization reaction. The reactor was operated at pressures> 400 psig and temperatures above 70 ° C. Ethylene conversion was maintained in the reactor by controlling the catalyst injection rate. The residence time was relatively short (less than 30 minutes). Ethylene conversion per reaction cycle was greater than 80 wt% ethylene.

  Upon exiting the reactor, water and antioxidant additives were injected into the polymer solution. Water hydrolyzed the catalyst and stopped the polymerization reaction. Some additives such as antioxidants stay with the polymer and function as stabilizers to prevent polymer degradation. The post-reactor solution was heated from the reactor temperature (> 70 degrees Celsius) to 210-260 degrees Celsius in a two-stage devolatilization preparation to recover the solvent and unreacted monomer. Residual volatiles in the polymer were less than 2,000 ppm by weight. The polymer melt was pumped to a die for underwater pellet cutting.

Release Layer The release layer is a low density polyethylene and optionally a linear low density polyethylene having a density of 0.920 g / cc and a melt index I2 of 1.0 (DOWLEX ™ 2045G available from Dow Chemical Company) Consisting of a blend of The LDPE resin used in the release layer is shown in Table 2 below. All LDPE resins are available from Dow Chemical Company.

Film A three layer blown film was made using a Hosokawa Alpine 7 layer blown film line. An adhesive layer (outside the bubble) having a layer ratio of 15% is produced from the extruder 1. Core layers having a layer ratio of 70% are produced from extruders 2, 3, 4, 5 and 6. A release layer (inside the bubble) having a layer ratio of 15% is produced from the extruder 7. All extruders are groove feed and the L / D ratio is 30 with a diameter of 50 mm. The extrusion melt temperature for all extruders ranges from 450 to 480 ° F and the die temperature is 450 ° F. The die gap is 78.7 mils. The blow-up ratio is 2.5 and the film gauge is 1 mil. The output speed is 300 pounds / hour. The film structure is further summarized in Table 3 below.

  While the film of the present invention shows a good combination of low noise value and sufficiently high adhesive strength, the comparative film has an adhesive strength, especially as the amount of LDPE present in the release layer increases. Shows a marked decrease.

  The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”.

  All references cited herein, including any cross-referenced or related patents or applications, and any patent applications or patents for which this application claims priority or benefit, are expressly indicated. Unless otherwise stated or otherwise limited, the entirety of which is incorporated herein by reference. Citation of any reference is prior art to any invention for which the reference is disclosed or claimed herein, or the reference is independent or any other reference (s) ) Is not admitted to teach, suggest, or disclose any such invention in any combination with (a). In addition, to the extent that any meaning or definition of a term in this document contradicts any meaning or definition of the same term in a document incorporated by reference, the meaning or definition given to that term in this document shall govern And

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. . Accordingly, it is intended by the appended claims to cover all such changes and modifications as fall within the scope of the invention.

Claims (15)

A multilayer film comprising an adhesive layer and a release layer,
The adhesive layer is
(I) an ethylene / alpha olefin elastomer having a density in the range of 0.855 to 0.890 grams / cm ³ and a melt index I ₂ in the range of 0.1 to 30 grams / 10 minutes;
(Ii) a polyethylene polymer selected from ultra-low density polyethylene, very low density polyethylene, or combinations thereof, wherein the polyethylene polymer has a density in the range of 0.885 to 0.915 gram / cm ³ ; A polyethylene polymer having a melt index I _{2 in} the range of 1-30 grams / 10 minutes and a purge fraction greater than 20 percent as determined by the Crystallized Elution Fractionation (CEF) test method. ,
The release layer is measured with a density of 0.915-0.930 g / cc, a melt index I ₂ of 1.0-30.0 g / 10 min, and a conventional calibration of triple detector gel permeation chromatography. A multilayer film comprising low density polyethylene (LDPE) having a molecular weight distribution Mw / Mn of 0.0 to less than 7.0.   The film of claim 1, wherein the release layer comprises 85 wt% to 100 wt% of the LDPE.   The film of claim 1, wherein the low density polyethylene has a number average molecular weight of 10,000 to 20,000 g / mol as measured by conventional calibration of TDGPC.   The film of claim 1, wherein the low density polyethylene has a Mw (abs) / Mn (conv) of 1.5 to 2.1 as measured by TDGPC.   The film of claim 1, wherein the low density polyethylene has a gpcBR of 1.0 to 1.9 as measured by TDGPC.   The low density polyethylene has a viscosity ratio of 7-15 (viscosity at 0.1 rad / sec divided by viscosity at 100 rad / sec, both measured at 190 ° C. using dynamic mechanical spectroscopy). The film according to claim 1.   The film of claim 1, wherein the low density polyethylene has a loss tangent of 4.5 to 10 at 0.1 rad / sec as measured at 190 ° C. using dynamic mechanical spectroscopy.   The film of claim 1, wherein the release layer further comprises linear low density polyethylene.   The film of claim 1, wherein the adhesive layer comprises 20 wt% to 100 wt% of the ethylene / alpha olefin elastomer.   The film of claim 1, further comprising a core layer positioned between the adhesive layer and the release layer.   The film of claim 1, wherein the adhesive layer has a thickness that is 10 to 30 percent of the total thickness of the film.   The film of claim 1, wherein the release layer has a thickness that is 10 to 30 percent of the total thickness of the film.   The film of claim 1, wherein the film exhibits an adhesion value of greater than 200 g when the release layer comprises 100 wt% LDPE.   The film of claim 8, wherein the film exhibits a noise level of less than 90 dB when the release layer comprises 100 wt% LDPE. A method for producing a multilayer film according to any one of claims 1-14,
Coextruding the adhesive layer composition with the release layer composition in an extruder to form a tube having an adhesive layer and a release layer;
Cooling the tube to form a multilayer blown stretched film.